The present invention relates to a camera that can record an image of an object to be photographed using a CCD (Charge Coupled Device), and more specifically, to a camera in which image data obtained using a CCD is compressed and recorded.
Recently, digital cameras which electronically store data related to a photographed image have become popular. The digital camera converts the optical image to electronic image data and digitally records the image data on a recording medium, such as an IC card. When the image is reproduced, the recorded digital data is retrieved from the storage medium and displayed on a display device or printed out as a hard copy image.
Generally, a CCD receives the optical image and outputs an electrical signal corresponding to the optical image. The electrical signal is A/D converted, then stored on a recording medium, such as a floppy disk or an IC memory card. The CCD is constructed such that photoelectric elements, such as photodiodes which convert the intensity of light into an electric charge, are arranged in a matrix. The charge generated in each element is transferred in vertical and horizontal directions. Thus, the image data for one image frame, which is obtained by exposing the CCD to an object image, is outputted as a series of data and transferred by horizontal and vertical CCD shift registers HCCD and VCCD, respectively and recorded onto the recording medium.
In this type of camera, since the size of the image data outputted by the CCD is large, if the image data is recorded as is, the recording medium can store only a small number of pictures. Therefore, the image data obtained by the CCD is compressed before it is recorded. When reproducing the image, the compressed data is read out and expanded.
If the camera uses the above described system, since the compression takes a certain period of time, the data outputted by the CCD should first be stored unmodified, in an image memory (a field memory or a frame memory). Then, the stored data is compressed. With this construction, a large capacity image memory is required, since a large amount of data must be compressed. However, a large capacity memory is physically large, resulting in the overall size of the camera being large. Further, a large capacity memory is expensive, thereby increasing the cost of manufacturing the camera.